lactose intolerance dna

Can Our Genes Make Us Lactose Intolerant?

Many of us eat dairy products with no problem at all but others experience real problems which can cause great physical discomfort. Is this something genetics has a hand in or is it other factors at play?

In fact, it is estimated that around 20% of the UK population is currently lactose intolerant. But is the answer to lactose intolerance to be found in our genes?

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Understanding Lactose Intolerance

Lactose is a sugar found in milk and dairy products. It is broken down during digestion by an enzyme called lactase. Lactose intolerance occurs in people who do not produce enough lactase, meaning that lactose enters the large intestine and literally stays there and ferments. It’s this fermentation which produces the symptoms of stomach pain, bloating and diarrhoea. So, the cause of lactose intolerance is that you aren’t producing enough lactase enzymes. 

What Do You Experience If You Are Lactose Intolerant?

It is common, 30 minutes after eating lactose, to start to expertise a range of symptoms. These can include bloating, cramps, gas, diarrhoea and even vomiting. Many people will immediately feel better if they change something simple in their diet like milk, replacing it with lactose free milk. This act in itself can be an indicator that you are lactose intolerant.

What Can Lactose Intolerance Get Confused With?

The symptoms of lactose intolerance are very similar to other conditions and may explain why sometimes it is not diagnosed properly. One example is irritable bowel syndrome. This is a long-term disorder of which the exact cause is unknown. It is however known to be linked with oversensitive nerves in your gut, stress and a family history of the condition. Another condition is milk protein intolerance. This is an adverse reaction to the protein in milk from cows, it again leads to similar symptoms to lactose intolerance but is not the same as lactose intolerance.

Is Lactose Intolerance An Allergy?

No, it isn’t. An allergy occurs when your body sees a substance as dangerous and reacts accordingly so you will have a rash, your breathing will be affected, your tongue may swell, and you may even lose consciousness. In this sense a food allergy causes your immune system to react. An intolerance is not caused by your immune system. The difference between an allergy and an intolerance is also found in the time it takes you to react. So, an allergy usually causes an immediate reaction whereas an intolerance can take several hours. A food intolerance, despite making you very uncomfortable and feel ill is also not life threatening whereas an allergy can kill you. You can be allergic to milk and dairy products but again this is not the same as lactose intolerance. Other food items that you can be allergic to include shellfish, eggs, fish and nuts.

Do You Inherit Lactose Intolerance?

Lactose intolerance does seem to run in the family but also seems to be affected by your ethnic group. So, research suggests that 2-10% of North Europeans are lactose intolerant whilst it seems to affect more Asians and Africans. It can also be triggered by certain events like another disease or having a short-term illness and can happen if you have surgery on your small intestine. In these cases, the lactose intolerance can remain or can go away. But let’s return to the issue of genes.

Gene And Lactose Intolerance

There does appear to be a link between our genes and lactose intolerance. Lactase production depends on your LCT gene found on chromosome 2. This gene provides the instructions for making lactase. If this gene is working properly then you should produce enough lactase and experience no problems. But variants to this gene will affect production of lactase and therefore cause the intolerance. It seems that the gene MCM6 regulates the LCT gene, any problems here and you will probably have problems with lactose.

Can A DNA Test Prove You Are Lactose Intolerant?

If you suffer from what we call primary lactose intolerance, then a DNA test will tell you if you are intolerant. But it won’t work on those we call secondary lactose intolerance or those people who developed it not as a result of genetic variation but because they had an operation or an illness.

What can also complicate DNA testing for lactose intolerance is that we know some babies show signs of this yet then grow out of it. This is referred to as developmental lactose intolerance.

So whilst a DNA test may not be able to conclusively tell you if you you are lactose intolerant what it will be able to tell you is how much lactase enzyme you produce which in turn we know is the cause of primary lactose intolerance.

How Do You Treat Lactose Intolerance?

There is no cure that for example suddenly causes you to start producing enough lactase. The simplest solution is to alter your diet, to remove lactose from it. This can be done by buying more lactose free dairy products. In addition, you could also consume probiotic yogurt which is known to help with the symptoms of lactose intolerance. In addition, we now know that these yogurts add bacteria into our intestines, and it seems these bacteria produce their own lactase enzyme. The aim here is to try over time to help your body build up greater lactase content in the gut so that you can cope better with lactose.

Home Test Kits For Lactose Intolerance

You can now find home DNA testing kits for primary lactose intolerance. Most claim to have an accuracy of 99.5%, most rely on a saliva sample so are very easy to do. It is not recommended that you test young children as they will not normally have developed the symptoms of lactose intolerance.

DNA Tests For Other Food Intolerances

DNA home testing kits can also be used to test for a range of food and non-food intolerances. Some providers look for as many as 800 trigger items, looking at pollens, and pets alongside food items. Some of these tests use hair samples rather than saliva. Hair testing is often the preferred approach as it is unaffected by a person’s recent activity and allows an assessment to be made over a longer period of time. Other test providers may ask you to provide a blood sample which is a finger prick which enables them to test your body’s immunoglobulin G immune response.

What To Look For When Purchasing A Test For Food Intolerances

There are a number of providers in the market offering you an analysis of your response to different food items. When selecting a provider we would recommend that you consider the following:

  • Look very clearly at the detail of the foods they assess you for. This may sound obvious but different companies do test for different foods. It may be worth bearing in mind that the most common sensitivities that cause symptoms are lactose, sodium, caffeine and gluten.
  • Check the reliability of the testing procedure. You need to look at laboratory accreditations and any overall % accuracy calculation.
  • See what is offered after the test. Some test providers offer you dietary advice and even plans and contact with dieticians who can help you make changes based on the results.
  • Some providers will also offer you personalised vitamin supplements based on your results. This can be very helpful but do check that they are based on your results and are as bespoke as promised.
  • Some providers also offer you a monthly subscription set up for food intolerance testing. This can be quite useful because if you take a test every month or every quarter you can then see how any dietary changes are then altering any food sensitivities that you have. But do check the cost implications before you sign up.
  • Some companies will also transfer DNA samples from other companies, so you don’t have to submit another sample.